diff --git a/RhSolutions.AddIn/Services/RhExcelWriter.cs b/RhSolutions.AddIn/Services/RhExcelWriter.cs
index 51d66c6..2916dc2 100644
--- a/RhSolutions.AddIn/Services/RhExcelWriter.cs
+++ b/RhSolutions.AddIn/Services/RhExcelWriter.cs
@@ -249,7 +249,7 @@ public class RhExcelWriter : IExcelWriter, IDisposable
 
     public void Dispose()
     {
-        _progressBar.Dispose();
-        _resultBar.Dispose();
+        _progressBar?.Dispose();
+        _resultBar?.Dispose();
     }
 }